Yes the Assests looks good, but with them I can't sell my game right?
And even if so.
How does it look, if everyone would use the same Assets for a new game
Then they say...oh look... this game looks the same as XYZ.
This is the main problem of buyable Assets, I think.
Maybe it is good for playing around and learning, but I don't think it will be useful, when you want to sell the game later.

The free edition of unity is okay.
If I really going to sell something one day, the price for the PRO Version is no problem.
At UE4 you pay 5% of your earnings, which might be much more, when the game sells good.